Thread guide and tensioning system for sewing and similar machines



April 4, 1961 J. NEUKIRCH 2,977,909

THREAD GUIDE AND TENSIONING SYSTEM FOR SEWING AND SIMILAR MACHINES Filed Aug. 7, 1958 3 Sheets-Sheet 1 INVENTOP -7abdrrne A/[Uk/PC April 4, 1961 J. NEUKIRCH 2,977,909

THREAD GUIDE AND TENSIONING SYSTEM FOR SEWING AND SIMILAR MACHINES 3 Sheets-Sheet 2 Filed Aug. 7, 1958 April 4, 1961 J. NEUKIRCH 2,977,909

THREAD GUIDE AND TENSIONING SYSTEM FOR SEWING AND SIMILAR MACHINES 3 Sheets-Sheet 5 Filed Aug. 7, 1958 IN VEN TOR. Jame/war Mew-mm BY W @fi United StatesPatent THREAD GUIDE AND TENSIONING SYSTEM FOR SEWINGAND SIMILAR MACHINES 1 Johannes Neukirch, Bad Durkheim, Germany, assignor to This invention'relates to a thread guide and tensioning. system for use in connection with sewing and similar machines. 7 I

vIt is one of theprimary objects of the invention to provide means for substantially avoiding wear and stress onlthe sewing thread during feeding, guiding and tensioning same in the course of sewing, stitching and like operations. i

' It is another object of the invention to provide means conducive to a very eflicient, smooth and accurate sewing operation, in which the sewing needlewill not be subjected to bending or distortion stresses and is at all times guided together with the upper spool thread passing through it in a rather positive and substantially frictionless path, during which the thread does not unfavorably act on or aflect the needle. i 1 V Yet a further object of the. present invention is to provide means redounding to asubstantially noiselessworking needle motion transmission and vto a sewing thread tensioning system, whereby a thread gui de isso interposed therebetween as to ensure marked elimination of strain and stresses on theneedle eye and on the: thread ice A existing sewing machines, as simple thread guide or deflection means may be attached thereto, which overcome considerable drawbacks heretofore experienced by operators applying and working with double stitch seams.

, In conventional sewing machines of the aforesaid type the thread guide arrangement is such that the upper thread before passing through the eye of the needle is deviated and conducted over a take-up lever the function of which is to tighten the loop of the thread formed in the course of each stitch. With each take-up action that occurs with each stitch the upper spool thread will be retracted or moved back through the needle eye.

passing therethrough, andto reduce to a minimum" disturbances in the running sewing operations, repainand thread breakage. i 1 i A n It is still another object of this inventionto provide means offering the possibility of employing an upper spool thread in double stitch sewingopera tions which thread passes the eye of the needle with'aminimum .of

obstruction or hindrance, so that theioperational conditions of the transfer mechanism and bobbin diameter for the lower thread can be advantageously influenced to comply with highly desirable practical and economical requirements. i

Yet a further important object of the present invention resides in the provision of means maintaining conneedle, while during feeding of the thread no laxness of the same takes place.

Still another object of the present invention is to pro vide means imparting to the sewing thread during feeding thereof from a supply spool a substantially downward direction even after said thread has passed through the eye of the needle and while the loop of the thread is being tightened and subjected to contraction.

A further important advantage of the present invention is to be regarded in arrangement of thread guide means in any appropriate form, such as a roller, pin and like round or arcuate-shaped element on a presser foot or like part and laterally of the path performed by the needle and between the latter and the swing arm of the take-up lever of the sewing machine.

A still further object of the present invention is to provide means markedly enhancing the speed and accuracy of the sewing machine operation and without substantially increasing the production cost of known or stant at all times during operation of the needle bar the length as" well as the direction of-the sewing-thread between the thread tensioning device and the eye of the not be realized, because of the greater risk of the thread failure or breakage and needle strains due to the employment of greater sizes of the loops.

. Various arrangements of the take-up lever have already "been proposed, in order to overcome the difiiculty with respect to the strains upon the upper thread. But

they did not avoid this difiiculty for the reason that the l thread had to enter the eye of the needle at an acute 30 angle for tightening the loop. This meant that the path angle from above, only to be retracted again under an of the thread through the needle eye represented an acute angle, with the thread subjected to the unfavorable effect of the relatively sharp edge in the needle eye along which it had to pass.

The concept forming the basis of the present invenition is to provide a thread guide arrangement in which the upper thread coming from the supply spool is engaged ,by' the take-up lever only after it has passed through the needle eye, and to so improve the operation "that practically all unfavorable'effects upon the upper 'thread are eliminated, thus rendering it possible to increase the speed of the sewing operation, as well as to employfgrippers and lower thread bobbins presenting greater thread capacity.

ing the thread in such a manner that the thread when the loop is tightened, will pass through the needle eye downwardly without any substantial change of its direc- 'tion of feed. This makes it possible for the take-up lever to pull the thread through the needle eye substantially without incurring or producing any friction.

The aforesaid guide member for the upper spool thread provided according to the invention may, however, assume a variety of forms and the mounting may be arranged in various ways. For example, it may be in the form of a roller, pin, or wire bail, which may be attached to or form a suitable sewing machine part, such as the presser foot.

Also, according to the invention, the take-up lever may be arranged on the needle bar, so that the distance between the needle eye and the take-up arm and therefore also the direction of the feed or supply thread will remain unaltered.

Further features and detailed advantages of the invention will appear from the following description of an embodiment of the invention illustrated in the accompanying drawings, which disclose the novel thread guide arrangement pursuant to this invention:

Fig. 1 is a front elevational view of the invention;

Fig. 2 is aside elevational view; and,

Figs. 3 'to- 6-show various stages of cooperation ofthe needle with the gripper means of the thread guide system according to the invention.

The outlineof the 'head or frame A of the sewing machine is indicated in the drawing in dotted lines. The needle actuating mechanism arranged in the head com prises a crank drive transmission actuating the needle bar A which carries athread tensioning device or means a. The needle bar A carries at its end the needleg which has a needle eye g through which passes the upper spool thread h derived from a spool i. The thread h is entwined about the thread tensioning means a.

The upper thread h after passing a guide b is threaded through the needle eye g and is engaged by a take-up mechanism d having an arm d" pivotally mounted on a suitable linkage at at d, which'arm is actuated by the crank drive 1 via said linkage, which drive also reciprocates the needle bar A by way of crank arm b.

A light spring arm e mounted on the frame is shown to act as tensioner or guide for the thread, although such a'spring could also be directly associated with the spool i proper.

According to the invention, special additional guide means are provided for causing the thread to be pulled downwardly through the needle eye in'the course of the sewing operation in such a manner that it is never subjected to any significant amount of friction or wear in the needle eye g. Accordingly, in the preferred embodiment of the invention, there is provided a guideelement c for the'thread interposed in the path of the thread 'h andbetween the needle g and the take-up arm d" carriedby an 'arm p extending laterallyfrom the presser foot m which extends downwardly from the conventional presser bar m. Guide element c'is located in a plane intermediate the path of needle g and said loop h.

According, in the operating condition shown inthe drawing the upper thread passes from-the source of supply or spool i over the thread tensioning means a down through the needle eye and further down from the needle eye a short distance, thereafter around the arcuate guide element then to rise again upwardly under an angle to be engaged by or looped on the take-up arm d".

The bobbin or shuttle providing the supply of the lower threadis carried by gripper means k in a conventional manner.

-In;the sewing operation, whenever the take-up arm d" tightens up on the thread loop h, the needle eye g is so located relative to the guide element 0 that the upper thread h is pulled downwardly from the needle eye g without being subjected to any significant amount of friction.

Consequently, when the needle bar reciprocates, the

length of thread 'h and the direction of its path-between the thread tensioning means a and the needle eye .3

against producing any slack in -the thread feed between the thread supply spool i and the thread tensioning means a which latter reciprocates together with the needle bar A. As a result with the improved thread guide arrangement of this invention, it is possible .to operate with a large thread loop h which in turn provides the possibility for using llower'threa'd gripper means of large diameter and lower thread supply bobbins of high thread capacity.

Various changes and modifications may be made without 'departingfrom'the spirit and scope of the present invention and it is intended that such obvious changes and modifications be embraced by the annexed claims.

Havingthus described the invention, what is claimed asnew and'desired to be secured by Letters Patent is: 1. A thread guide system for a sewing machine having a frame, comprising a needle bar mounted in said frame, a sewing needle having an eye and depending from said needle ban-a presser-foot mounted on said frame adjacent said-sewing needle,-drive means for reciprocating said needle being located in said frame and being connected to said needle bar, a'take up lever pivoted to said frame andbeing mounted adjacent said sewing needle formovement froma raised positioned to a lowered position,

lever means for oscillating said take up lever so that said take up lever is in a raised position when said sewing needle'is in-a raised'position and so that said take said needle is in a raised position, said guide means ex- "tending in a plane'located intermediate the path of move- "ment-of said needle and said take up lever for guiding "thread being fed through said eye without substantially changing the direction offeed of the thread upon motion 10f said take up lever.

f2. Thread guide arrangement according to claim 1,

Linwhich said arcuate shaped thread guide means is inthe "form of a roller.

3. Thread guide arrangement according to claim 1,

in which said arcuate shaped thread guide means is in theform of a pin.

'4. Thread guide arrangement according to claim 1,

'in'whichflsaid arcuate shaped thread guide meansisin theformof a wire bail.

*"ReferencesCited in the file of this patent UNITED STATES PATENTS 566,767 Jerram Sept. 1, 1896 FOREIGN PATENTS 873,199 Germany Feb. 26, 1953 

